1. Field of the Invention
The present invention relates to backlight modules, and especially to a backlight module with a switch element used in digital products such as liquid crystal display (LCD) devices and the like.
2. Description of the Prior Art
Liquid crystal displays (LCD) are now in widespread use in various applications; for example, in desktop computers, portable computers, LCD televisions, portable telephones, etc. An LCD cannot emit light itself. A light source system such as a backlight system is needed for emission of light. A light guide plate is an important part of a backlight system, because it controls uniform directionality of emitted light.
A conventional backlight module is shown in FIG. 5. The backlight module 1 comprises a light source 11, a light source cover 16, a reflection plate 12, a light guide plate 13, a diffusion plate 14, and a brightness enhancement film (BEF) 15.
The reflection plate 12, light guide plate 13, diffusion plate 14 and BEF 15 are stacked sequentially from bottom to top. The light guide plate 13 is flat, and includes an incident surface 131, a bottom surface 133 substantially perpendicular to the incident surface 131, and an emitting surface 132 opposite to the bottom surface 133. The light source 11 is arranged adjacent to the incident surface 131, and the light source cover 16 essentially covers three sides of the light source 11. The BEF 15 has a plurality of parallel prism sections 151.
Light beams emitted by the light source 11 enter the light guide plate 13 through the incident surface 131 and propagate through the light guide plate 13. The light guide plate 13 cooperates with the reflection plate 12 to guide the light beams to emit out from the emitting surface 132. Then the light beams are diffused by the diffusion plate 14, and are focused by the prism sections 151 to supply bright light for an associated display screen.
In recent years, the development of liquid crystal display devices has paralleled the development of digital products, particularly digital products which have photography functionality such as mobile communications devices and digital video. To enable photography and filming, these products generally need an amount of artificial light like a flash in low light conditions. However, conventional backlight modules are not equipped to meet this requirement.
Therefore, it is desired to provide a backlight module which overcomes the above-described shortcoming of the prior art.